This invention relates to a fundamental transverse mode controlled semiconductor laser device and more particularly to a semiconductor laser device adapted to be fabricated by metal organic chemical vapor deposition (hereinafter referred to as MOCVD) method and a method of fabricating it.
A conventional typical transverse mode structure of the semiconductor laser made by MOCVD method was such as shown in FIG. 1, which is disclosed in J. J. Coleman et al, APL. 37 267 (1980). As seen from FIG. 1, a p type Ga.sub.1-x Al.sub.x As layer 6 is formed on a double hetero structure consisting of an n type GaAs substrate 1, n type Ga.sub.1-x Al.sub.x As layer 2, and flat GaAs active layer 2 which are successively formed; and n type GaAs layer 4, which will act as an optical absorption and current blocking layer, is formed within the p type Ga.sub.1-x Al.sub.x As layer 6 while a stripe region 5 is left there; and a p side electrode 8 and n side electrode 9 are provided on the surface of a p type GaAs layer 7 formed on the p type Ga.sub.1-x Al.sub.x As layer 6 and the back surface of the n type GaAs substrate 1, respectively. The structure shown in FIG. 1 allows light generated in the GaAs active layer 3 to be absorbed in the n type GaAs layer 4 at the exterior of the stripe region 5, which gives rise to a difference of effective refractive index between the interior and exterior of the stripe region 5 thereby to perform transverse mode control.